Turbine-blade fastening



Aug. 9, 1927.

H. R. 'rRoT-rlz-:R -E1" Al.

TURBINE BLADE FASTENING Filed Amm. 192s Sen Murr. INVENToRs BY ATTORNEY ,Z &\\\\\\\\\\\\\A /4 Patented Aug. 9, 1927.

NETE@ maar HENRY R. TROTTER, OF SWARTHMOEE, AND HENRY F. SCHIVIDT, OF LANSDOWNE, PENNSYLVANIA, ASSIGNORS TO WESTIGHOUSE ELECTRIC AND MANUFACTUR- ING- COMPANY, A CORPORATION'OF PENNSYLVANIA.

TURBINE-BLADE FASTENING.

Application filed August 13, 1923. Serial No. 657,211.

Our invention relates to turbines and more particularly to apparatus for securing the blades thereof to a blade-carrying element and it has for its object to provide apparatus of this character which shall assure a strong and durable fastening of the blades without any undue stressing of the blade root portions. v

It is old in the art to provide a turbine blade which has a substantially Tsliaped root portion iitting in a similarly shaped groove of a blade-carrying element. lt has been proposed to associate wedges with various portions of the T-root portion in order that the latter may be rmly engaged in its groove. It is the object of our invention not only to assure a better connection with this type of fastening, but also with other types of fastening hereinafter shown and described. ln general, we provide a blade root portion which is diyided or bifurcated longitudinally the top of the groove so as to provide relatively long arms which may be spread by appropriate wedge means in order that the root portion may be firmly engaged in its groove without undue stressing or fleXure of any of the parts of the root, thereby assuring a good fastening and the preservation of the strength of the root portion. rlhe wedges for spreading the arms of the root portions may be effective either longitudinally of a blade or transversely with respect thereto. means may be employed, in which case, one wedge means may be effective longitudinally of the blade and the other wedge means may be effective transversely of the blade in order to render the first wedge means effective or the elements of the compound wedge means may be both effective transversely 'of the blade root portion. Vith any of the types of wedges referred to, a uniform spreadingy of the root portion so asvto firmly engage the latter with the blade holding groove is as sui-ed. Y Y

Apparatus made in accordance with our invention is illustrated in the accompanying` drawings, forming a partof this application, in which Fig. 1 is a sectional detail view showing a T-,formof blade connection with compound wedges; Fig. 2 shows a similari root connection ywith a different arrangement of wedges; Fig. 3 is a view similar to of the blade and well toward Also, a ycompound wedgey Fig. 1 but showing a single transverse wedge; Figs. 4, 5l and 6 show countersunk T-form blade connections with different types of wedge means for spreading` the root portions; and Fig. 7 is a detailview of a serrated type of connection with Vwedge means for spreading' the blade root portion. l Referring now to the drawings for a better understanding of our invention, in Fig. 1, we `show a blade-carrying element 10,

which may-be the rotor or the stator of a i steam turbine or like apparatus, having a blade groove 11 with lateral recesses 1Q at the bottom thereof. A blade 13 has a root portion 14 provided with lateral projections 15 which lits in t-he groove 11. The root portion 14 is divided or bifurcated so as to provide an intermediate recess 16 having inclined walls extending from the bottom end of the blade root portion adjacent to the top of the blade groove 11 and having inclined walls for the reception of a wedge 17, which is effective longitudinally of the blade in 'order to spread the root portion to firmly engage the sides of the bladeholding` groove-11. In Fig. l, the wedge 17 is forced upwardly in order to spread the root portion 1n the manner stated by means of a second wedge 18, which is ylocated inthe bottom of the blade holding grooves 11 and which when driven in the direction of extent of the blade rootr11 not only forces the wedge 17 up in the manner stated, but also,

cooperates to force the projections 15 tightly up into contact with the top walls of the recess 12.

The wedges 17 and 18 of Fig. 1 may be duplicated, thereby facilitating manufacvture and assembly.

Fig. 2 shows a blade groove 11 and a blade root portion 14 4which is similar to those lshown in Fig. 1. 4ln this view, the blade f `'In Fig. 3, we sh'oxv abla'de holding` groove mii., i

11 and ya bladeroot portion 14 which are vieiv,l hoivevei-ithe root portion v14vis bifurf lcated orY divided in order to provide .a transverse recess 23 having a portion 24 Vat the Y K' top thereof with inclined Walls-'extending' -transversely of the bladel or in the direicne j-,20

tion'of extent of the blade lioldiiiggroove 1,11 fory the reception of a Wedge 2 5 vvh1ch V is drivenlin Athe.;direction,,ofA the blade groove tard-holdinggroe;

We showivvhat may be termedba eoiintersunlr i-forme @tween-oa; grue-blade hqiding elfe? ment 10, ofthe 51 jiirbi'iie is provided With .la

y y 33 fittingrespectivel l f inclinedtransversely or; in th'e dii l Y the blade groove 27 for ythe;reception {ofa v'vedge 36, Y which i'sx'driveir in' thee direction.

neclportion 34ivliicliv'fitsthe neel: portion 30 of the recessHhTl-ieblade ro't portion is divi'dedor bifiircatedfsola-szto provide Vanf, interrnediateY recess extending frein the bottoni: eithe ,rootH-portion Well tmvardthe Y top thereof ,i andin-thebqttom, this recess of said Vblade groove ill .order the, root finfay Vbe spread to firmly engage ni blaat iioiaing groeve.,

innig. sgiifeshow a bladeleiding-rijm j 27 and a blade -.root portion 81Wliich are similar lt0 Y @Responding rafts Shea/11 in only.dffeehebemgm ,theme 'tyieffw L f connection ea'chas shown in' gs. y 6 5 In this view We show ablade `root 'portion We *show owedge means employed.- 'In-fthisf vievv,

edge in' nsf r Ya] am@ portieri 31 pqvidedwth fingzat'any point; -Also,I'asample deflection may be providedivith u-rCOIstr-uction' it is .possible Ato provide blade roots" 4,Whichaaie su'fei'eiitly Asiii'aller than the' blade .holding ssist-iiisprea the bladefroot.

which 'is' yor` bifiircated te provide i a complemental recess 41 for the reception the bladeffroot 27 by relative displacement` ofone Wedge portionv42 with respect to .the

sulting in anincrease Vin the effective Width ,of the Wedge construction andconseqtientfeadingof the arms of the bifurcated root portion., 1

iai-Tie eonnectionwhich employs a wedge construction somewhat like that already described in connection with lFig. 2.5111', .tliisevievv,

We show a blade-carrying element 1()l hav.-

ying` abladegroove 4 5-'Whose Wallseonverge de ivnivardlygand which are Aprovided with serrations 46.' The bladeY 13 isV .provided Vwith. a iconvergii'i'ggroot portion 47 having` lateralgserr-ations 48 for engageinentL with the serrations 46 of the bladeagroove 145;

The reet portien- 47 Ais* divided .onbiiircated Y inl order to provide an intermediate recess 4S) Vwhich extends from( the'V bottom of `the Yroot portion' Well-toward the top. thereoi.

lli'erecesrsv49 converges Vdownwardly vand a wedge V5Qiit`s therein. A second VWedgel is arrangedl above` the Wedge 50 andg when it is `driven homei-t forces thef-Wedgeo downwardlyl in order tospread the root portion 47to lirinly engagefit With the sidesA y7,V We show amodiliedltype of root Aother' prtioi'il 43.1Such displacement re- Y tliatpthe for/.ce of. the Wedgejis distributed i onthe portions of the root to avoid concentrated lstresses-at any place. vIn this;v Way, all of thereotv portion is v effective `in they same manner 'con't'ei'nplated:A to'y hold the.r blade in b ifiirc'at'ed y lsubsta'nt'ial'ly throiighout f its length is-possibletovsecure the .requisite deflection of the arms Witliutiinde stress?V 'i grvs toi assure op easy'assembiyglth subsed-ieiitwvedgng operatins'f-'ibeiig ldepended A pponto securespreadingrof the root portions r in .order tofirinlyengfagethe blade'lolding V only suchy limitations shall lbe'V placed there.`

iis

VLiso 110 place;y Sii'iceeachrootvportion isdivided or upon as are imposed by the prior art or as are specifically set forth in the appended claims.

What We claim is:

l. In a turbine, the combinationy of a blade-carrying element having a blade groove therein with lateral recesses, a blade having a root portion with lateral projections to fit the groove and being divided longitudinally so as to provide an intermediate recessfhaving Walls inclined longitudinall of the blade, Wedge means fitting the inclined Walls of said recess, and second Wedge means for driving the first Wedge means longitudinally of the blade.

2. In a turbine, the combination of a blade-carrying element having a blade groove with lateral recesses, a blade having a root portion with lateral projections for fitting the blade groove and being divided in a longitudinal direction s-o as to provide a recess having Walls inclined longitudinally of the' blade, a Wedge located in the recess, and a second Wedge effective in the direction of extent of the blade groove and transversely of the blade for forcing the first Wedge into the recess longitudinally of the blade to spread the blade root portion in order that the latter may firmly engage the blade groove.

8. In a turbine, the combination of ,a blade-carrying element having a blade groove with lateral recesses, a blade having a root portion with lateral projections for fitting the blade groove and being divided in a longitudinal direction so as to provide a recess having Walls inclined longitudinally of the blade, a Wedge located in theV recess, and a second Wedge bearing on the firstmentioned Wedge and forcing it longitudinally of the blade into tighter engagement with the inclined Walls of the recess.

ll. In a turbine, the combination of a-blade carrying element having a blade groove therein With a lateral recess, a blade having a root portion with a lat-eral projection to fit the groove and being divided longitudinally so as to provide an intermediate recess having Walls extending substantially longitudinally of the blade and inclined relatively to each other, Wedge means fitting the inclined Walls of the recess, and second Wedge means separate from the first Wedge means for driving the first Wedge means longitudinally of the blade.

5. In a turbine, the combination of a blade carrying element having a blade groove therein with a lateral recess, a blade havingy a root portion with a lateral projection to fit the groove and being divided longitudinally so as to provide an intermediate recess having Walls extending substantially longitudinally of the blade and inclined relatively to each other, Wedge means fitting the inclined Walls of the recess, and second Wedge means separate from the first Wedge means effective when driven transversely of the blade for driving the first Wedge means longitudinally of the blade. i n l In testimony whereof, We have hereunto subscribed our names this 2nd day of August HENRY R. TROJTER. HENRY F. SCHMIDT. 

